Study On Failure Mechanism Of Thermoplasitic Composite Based On Explicit Finite Element Method

Fiber-reinforced resin matrix composites can be divided into thermoset composites and thermoplastic composites.Compared to thermoset composites,thermoplastic composites show the advantages of recoverability,higher specific strength and stiffness.Thus,thermoplastic composites exhibit a better application prospect in fields of aerospace,marine watercraft,new energy automobile and so on.However,the mechanical properties of thermoplastic resins such as PC and PMMA are very complicated.Mechanical properties depend on the loading rate,temperature and hydrostatic pressure,and show large deformation and creep behaviors.Besides,strain softening and localization problem appear after plastic stage and microscopic failure mechanisms include void growth,crazing,shear yielding and molecular chain rupture.However,the research on failure mechanisms for thermoplastic composites is little.Multiscale research is a key for composites.To establish the microscopic fiber/matrix/interface cell models,to propose theoretical method and numerical technique and to elucidate the failure mechanisms of composites are important to bridge the macroscopic and microscopic mechanical properties.Therefore,this paper first develops a finite-deformation nonlocal viscoplastic Gurson model and a nonlocal explicit finite element technique based on ABAQUS subroutine modules.The failure mechanisms of dumbbell,style polycarbonate specimen and the regularization effect of nonlocal averaging are studied.Then,microscopic cell models with randomly distributed fibers are established by combining with the cohesive model to predict the macro-micro failure mechanisms for thermoplastic composites under transverse tension and shear.Effects of nonlocal radius,fiber distribution and interface strength on the failure properties are discussed.Besides,the failure surface by numerical results is compared with those by Hashin and Puck criteria,which provides a research idea to predict failure mechanisms more precisely for thermoplastic composites from the multiscale perspective.The originality of this paper is to develop a finite-deformation nonlocal viscoplastic Gurson model and a nonlocal explicit finite element technique for thermoplastic resin with plastic softening.Mesh sensitivity resulting from strain softening is solved effectively and the convergence problem by implicit finite element analysis is avoided.This research provides theoretical and technical supports for predicting failure behaviors of thermoplastic composites effectively and accurately.